European Journal of Wood and Wood Products最新文献

Wood pellets constitute one of the most common solid biofuels that fulfil residential and industrial energy requirements. The high demands of raw materials have urged the search for alternatives to pure wood materials, such as residual biomass obtained from intensive agriculture. In this study, pellets that utilize biomass from pruning of olive trees (Olea europea L.) were produced, which is a species intensively cultivated in Greece and Mediterranean countries. The leaves, embarked branches of 3 different diameter classes (thin, medium, thick), as well as pure stem-wood have been examined as pellets feedstock material, both separately and in different materials mixtures, including the synthesis case of initial materials ratio recorded in pruning residues material. The pelletization process was performed using a single pellet die press at 120 °C applying the pressure of 3 tons. The raw materials were characterized in regard to ash content, calorific value, moisture content, while the produced pellets were characterized in terms of moisture content, density, dimensional stability and mechanical strength. According to the requirements of ENplus certification system concerning the biofuels feedstock properties, the olive tree pruning residues material, despite their high calorific value, cannot be used as pellets feedstock material in the specific form of recorded initial pruning materials ratio (leaves, thin / medium / thick branches). The presence of leaves appeared to increase the ash content and reduce the mechanical strength of pellets. The medium and thick branches could serve as feedstock of pellets of quality B for residential applications (as regards the ash content). Pure wood presented lower ash content, though it could be used as feedstock of pellets of quality A2 (not A1, due to ash restrictions), while it could be classified as B in a mixture with medium or thick branches. All the studied residual materials of olive tree bestowed the produced pellets with integrity and plasticity.

Models for predicting physical properties of wood in standing trees are useful for helping to make decisions about tree selection for harvesting and technological use of the material. The objectives of this study were to investigate the variation in physical properties of Douglas fir wood obtained from thinning and to construct a model for predicting wood density on the basis of easy-to-measure properties in thinned trees. Sixteen young Douglas fir trees growing in three stands in Galicia (NW Spain) were felled for the study. Small specimens of defect-free wood were obtained from the trees in order to determine annual growth ring width, density and shrinkage-related properties by standardised testing methods. The sampled wood was homogeneous and light (mean oven-dry density = 429 kg m^− 3), and the dimensions were stable in response to changes in moisture content (volumetric shrinkage from saturation to oven-dry state = 12.0%; ratio tangential/radial shrinkage, i.e. anisotropic shrinkage = 1.6). The density of wood in the sampled trees increased with the diameter at breast height and decreased with the height in the stem. The observed significant between-tree and intra-tree variation in wood properties was used to develop a model for predicting oven-dry density, with diameter at breast height and height in the stem as predictor variables (adjusted coefficient of determination = 0.57). The model is useful for estimating wood density along the stem in trees removed during thinning, and the results suggest selecting trees with diameter at breast height over 30 cm when dense wood is needed.

The challenge of creating cellulose-based materials resistant to fire, water, and are eco-friendly has surged in various industries. Innovative bio-based cellulose substances, especially those with robust fire and humidity resistance, are pivotal for high-quality cellulose-based packaging. This study focuses on TEMPO-oxidized cellulose nanofibers at concentrations of 2, 2.5, and 3wt%, modified using three chemical combinations: "ammonium dihydrogen phosphate + albumin", "silica + methyltrimethoxysilane", and a mixture of all four ingredients. Each combination, with a constant level of 14% and a coat weight of 3.5 g.m⁻², was applied to the surface of the produced paperboards. Flame retardancy analysis results indicate that modified TEMPO-oxidized CNF at 3wt%, employing the quadruple combination, offers suitable fire properties in the prepared paperboard, mainly due to intumescent phosphorus-based flame retardants. These retardants reduce the peak heat release rate as a function of the heat release temperature. Furthermore, silicon groups by blocking functional hydroxyl groups, induced hydrophobicity in cellulose nanofibers, as indicated by contact angle and water uptake measurements. Tensile strength significantly improved after incorporating wettable bio-retardants into cellulose nanofibers and coating them onto the cellulose matrix. Also, the roughness and homogeneity of the surface of the paperboard increased when the solid of CNF increased from 2 to 2.5, and 3wt%, respectively according to the FESEM analysis. This modification system offers potential as a foundational substrate for high-quality pharmaceutical and hygienic packaging, providing degradable alternatives to non-recyclable plastics and achieving eco-friendly advantages.

Cross-laminated timber (CLT) has become a notable building material due to its structural efficiency, reliability and sustainability. In this study, the bending performance of three-layered CLT constructed from fibre-managed Eucalyptus nitens (E. nitens) was investigated under short-term and long-term loadings. Linear-elastic four-point bending testing was used to determine the maximum serviceability loading capacity before they reached the suggested deflection limits. A pilot study was conducted to investigate the creep behaviour of E. nitens CLT through long-term bending tests in a controlled environmental room. The study suggested that E. nitens CLT has higher serviceability loading capacity and lower creep ratio compared to CLT made from strength-class C24 spruce. The investigations of various configurations of E. nitens CLT panels based on structural grades implemented in top, cross, and bottom layers have revealed different short-term and long-term bending performances. The grade of transverse layers has been found to be the most important factor in improving the bending creep performance of E. nitens CLT. Two modelling equations were employed to perform curve fitting on the experimental creep ratio with time. The conventional power-law modelling tends to underestimate the longer-term creep ratio when compared to a recently developed nonlinear regression modelling equation that takes environmental conditions into account. The mean estimated creep ratio after 50 years was 1.77 for E. nitens CLT, and 1.89 for the C24 spruce CLT. The present study is a pilot investigation to increase the understanding of performance of the newly developed CLT made from fibre-managed plantations E. nitens, with particular emphasis on its creep behaviour. The results of this study provide valuable contributions for future research in this field, and ongoing commercial production of E. nitens CLT.

Slow pyrolysis can be used to convert residual agricultural biomass into energy-dense biochar along with its by-product, pyrolysis liquid, for diverse applications. Due to its high concentration of bioactive chemicals, pyrolysis liquid has gained interest as a potential wood protectant. This study aims to evaluate the efficacy of slow pyrolysis liquid from sugarcane bagasse (Saccharum spp.) for wood protection against fungi and termites and its water-leaching properties. Pyrolysis liquid was obtained from slow pyrolysis at a temperature of 500 °C, a heating rate of 10 °C/min, and a holding time of 60 min. Specimens of European beech wood (Fagus sylvatica) and Scots pine sapwood (Pinus sylvestris) were impregnated with pyrolysis liquid using different concentrations and dried at different drying temperatures. A higher drying temperature (103 °C) was found to promote the agglomeration of pyrolysis liquid inside wood cells and lower the leaching rate. Pyrolysis liquid was effective against termites (Reticulitermes flavipes) as a repellent and toxic agent at a concentration of 25%. Higher concentrations of 50% and 100% were required to protect against certain types of Basidiomycete fungi (Coniophora puteana and Rhodonia placenta, brown rots and Trametes versicolor, a white rot). However, pyrolysis liquid remains leachable in water, with 3-methyl-1,2-cyclopentanedione, 2,6-dimethoxyphenol, and phenol identified as the principal compounds leached from the treated wood. Further studies should focus on investigating formulation strategies to improve fixation, using the minimum product for extended efficacy, and minimizing impacts on human health and the environment.

The objective of this study is to improve the accuracy of damage identification of plywood boards by the approach of utilizing acoustic emission (AE) in conjunction with a backpropagation (BP) neural network model and elucidate the failure characteristics under varying working conditions. Six AE characteristic parameters were collected simultaneously at the time of loading test. The K-means clustering analysis method was used to describe the damage evolution process of plywood. Based on the correspondence between the damage degree and the AE characteristic parameters, the damage identification model was established using the BP neural network. The results demonstrated that AE parameters analysis is capable of effectively drawing the distinctions between three damage stages during the stress damage process. The proportion of shear failure of plywood is higher than tensile failure. K-mean cluster analysis revealed a strong correlation between damage types and AE peak frequency. The backpropagation neural network model is subjected to rigorous testing and training. The results show that the model has excellent performance in damage type identification. Therefore, the joint AE-BP model was found to be a considerably effective method to evaluate damage types for plywood products.

The aim of this study was to determine the elemental composition and the fibre morphological characteristics, chemical and fuel properties of wood from paulownia COTEVISA-2 clone growing on a plantation near Granada, Spain. The research was carried out on five boards representing five 5-year-old trees, taken from a height of approximately 2–3 m. Morphologically, COTEVISA-2 wood has fibres with mean length 0.923 mm, diameter 0.029 mm, lumen width 0.026 mm, and cell wall thickness 0.0015 mm. The slenderness ratio ranged between 19.27 and 64.31, the Runkel ratio between 0.060 and 0.4259, the rigidity index between 2.83 and 19.94, Mühsteph’s index between 0.1099 and 0.5082, and the flexibility coefficient between 0.701 and 0.943. Significant differences between trees were found for the values of morphological characteristics of fibres and the derived indices, apart from the solids index. Mean values of chemical properties obtained from two parallel determinations for each sample showed that the wood contains on average 48.15% cellulose, 27.48% lignin, 7.38% pentosans and substances soluble in cold water (2.38%), hot water (3.87%), ethanol (5.51%) and 1% NaOH (19.64%). The elemental composition of paulownia COTEVISA-2 wood is as follows: C – 49.06%, H – 6.19%, N – 0.43%, S – 0.021%, Cl – 0.05%. The wood contained 0.4% ash. The heat of combustion of paulownia COTEVISA-2 wood is 18.58 MJ/kg, and the calorific value is 17.18 MJ/kg. The results suggest that paulownia COTEVISA-2 is a promising wood for energy and paper production.

The use of aluminum sulfate (AS) as a chemical treatment for plant fibers aims to protect them against the aggressions of the alkaline environment provided by cement. This research aimed to understand the effects of treatment with AS (chemical modification) at concentrations of 0%, 4% and 11% on the surface of Kraft pulp of Pinus spp. and to evaluate the composites generated on the 28th day of curing and after 200 cycles of accelerated aging. The results suggest that AS is a surface modifying agent and will be homogeneously deposited on the surface of plant fibers. In addition, the experimental data showed that treatment with AS reduced water absorption by approximately 3% and apparent porosity by 10% in cementitious composites. In contrast, the limit of proportionality increased with both AS concentrations. Furthermore, the modulus of elasticity of the composites produced with the fibers treated with AS increased considerably in relation to that of the fiber-cement sample with 0% AS. The modulus of rupture (MOR) of the 4% AS treatment sample was considerably greater than that of the control sample, both on the 28th day and after the aging cycles. On the other hand, no considerable changes were observed in the MOR of the composites produced from fibers treated with 11% AS compared to the control. The specific energy of the fiber-cement composites with 4% and 11% AS was considerably lower than that of the control sample. These data reflect the methods of applying cementitious composites, which can be used in the manufacturing of covering tiles that yield better results in terms of the modulus of elasticity (MOE). On the other hand, those composites that obtained higher MOR and specific energy (SE) values may be suitable for the production of both tile and flat plates.

The recent publication of the European Regulation on deforestation, linked to the import and export from the European Union (EU) of certain commodities and products associated with deforestation and forest degradation, controls sustainable and legal sourcing of wood and wood-based products in EU. In this context, the accurate verification of wood species and their origin has become increasingly crucial. In this work, a multispectral camera was adopted to retrieve high resolution remotely sensed imagery of different wood samples exploring the spectrum between 440 and 860 nm. Eighteen wood species spectra were investigated. Starting from these spectra, linear discriminant analysis (LDA) proved that the band at 665 nm is the first discriminative feature, followed by 490 nm and 560 nm, respectively. Bands at 783 nm or higher wavelengths, i.e. the NIR region, discriminate selected species poorly. Using the first 4 linear discriminants, a classification of wood species was performed using the minimum Mahalanobis distance algorithm. The majority of species showed class accuracies between 0.7 and 0.9. However, some species showed poor performances. Cluster analysis involving all available spectra proved that the higher classification errors occurred between species of the same spectral cluster. This work shows the potentialities of adopting cheap and rapid screening tool (cameras) for separating selected wood species opening new scenarios to support industrial and commercial control processes.